What Is Preload On Mountain Bike Suspension?
When shopping for mountain bike suspension, you may see that some models have preload and others don’t.
So what exactly does preload do, and how does it affect the compression characteristics of your mountain bike’s suspension?
Mountain bike suspension systems can be confusing for novice riders, but understanding how to adjust the preload on your suspension system can make it much more comfortable and easy to use.
This article will guide you on when you should use it and how much you should change it. Here’s everything you need to know about preload on mountain bike suspension.
Preload refers to how much the shock absorber has already compressed before being ridden over an obstacle. You can adjust the preload to suit your weight and riding style and help ensure the most efficient use of your bike’s suspension, which helps keep your ride comfortable and fun.
What Does “Preload” Mean On Bike Suspension?
You can use preload to set the shock or spring to the appropriate range of operation within the suspension’s travel.
For example, increasing the preload may lift the bike higher on its suspension, keeping you near the top of its travel range.
Conversely, the bike will sit lower and closer to the bottom of its travel when there is less preload on the suspension.
There are two essential types of adjustability in bike suspension: high-speed and low-speed compression. High-speed compression describes how fast a shock’s or fork’s spring compresses.
It is called preload on mountain bike forks, and you can adjust it with an air shaft that pulls up on a tiny coil spring inside your fork or shock.
On the other hand, low-speed compression controls small bumps and keeps your front wheel on top of square hits.
Low-speed compression is also known as rebound damping because it influences how fast a shock or fork recovers after being compressed by an obstacle.
You can adjust preload with a high-speed compression dial on forks and a low-speed rebound dial on shocks. These adjustments control preload.
Your bike shop will adjust them for you before delivery so that your suspension works perfectly.
Many mountain bikes have dual air shafts, adjusting high-speed and low-speed compression damping separately.
You should be familiar with preload if you want to set up your suspension for different conditions. For example, you may wish to increase the preload when riding through mud.
Conversely, when riding in dry conditions, you may want to decrease preload so that your fork or shock recovers quickly after hitting a rock or root.
How To Use Preload Suspension on a Mountain Bike?
Knowing how to use preload on mountain bike suspension when setting up your suspension can be tricky.
First, you must adjust preload and spring tension to set up your coil-sprung suspension with high-speed rebound and set rebound damping.
Then, once you’ve dialed in these two things, it’s time to move on to other settings like low-speed compression or low-speed rebound.
You measure preload on mountain bike suspension in mm, and it’s essentially just a fancy way of saying that you’re setting your sag.
Sag describes how far your suspension compresses when you sit on your bike, and preload refers to how much force is holding it against that travel.
Setting your sag is critical to getting your suspension setup correctly. Your sag should be somewhere between 5 and 15 percent.
If you’re on a cross-country ride or an enduro, you want to go with a higher percentage of sag than if you’re heading out for a downhill race.
That extra spring force will help soak up small bumps and give you better control in corners.
Once you’ve set your sag, it’s time to think about preload. Remember that preload is a fancy word for how far your suspension compresses when you sit on your bike.
Depending on your mountain bike type, you can use different methods to change your preload.
The most basic way to adjust preload is by installing a shim. Shim your front fork if you want more preload at your current sag point, or shim your rear shock if you want less.
The diameter of these pieces of plastic determines how much force is holding your suspension against its travel.
So, running a standard mountain bike suspension and installing one 5mm thick will add 5mm of spring force to your setup.
The other way to adjust preload is by moving your air canisters up or down. Depending on your suspension design, you can move your air canister in and out of a sealed chamber.
Then, if you want more preload at your current sag point, slide that air canister into that chamber until it’s fully compressed.
However, if you wish to lessen the preload at your current sag point, slide that air canister back out of that chamber until you partially compress it.
How To Adjust Preload Suspension On Mountain Bikes?
Positive preload springs increase a bike’s overall spring rate, often without affecting its ride height.
Increasing preload without altering other aspects of your suspension setup increases your total spring rate—meaning it takes more force to compress your suspension than it would with no positive preload.
Adjusting preload on a mountain bike suspension can significantly affect how plush your bike feels.
The fork’s positive preload adjustment generally consists of a threaded collar at either end of your fork’s steerer tube.
These collars are often color-coded to make identifying them easier; adjust them until they match an up or down arrow etched into your steerer tube.
Most forks will also have an adjustment knob on top of each leg, near where it connects to your bike.
After setting your fork’s positive preload, don’t forget to check its negative preload adjustment. It is located either in your fork or shock and is adjusted the same way as positive preload.
However, reducing negative preload softens your suspension, making it easier to move through its travel but less responsive when you hit big bumps.
Therefore, you use it best when you want a plush ride on small bumps.
Once you’ve dialed in your fork’s preload, it’s time to focus on its air pressure, which you should adjust based on how much travel you want and how technical your trails are.
For example, lowering your air pressure too much can cause your fork to bob excessively, which wastes energy.
On the other hand, if you set it too low, your bike might handle poorly on climbs and feel sluggish when pedaling through sections of the trail.
Do I Want More Or Less Preload?
When setting up a mountain bike suspension, deciding how much preload you want is essential. Choosing more or less preload for a given situation depends on a few factors.
If you’re trying to pick between two bikes, ensure that your planned setup and riding style will allow you to use as much preload as possible in all your riding scenarios.
The same goes for your riding style. If you’re looking for comfort and stability, use less preload to avoid bottoming out when pedaling or traveling at high speeds over rough ground.
On the other hand, if you’re looking for control and a responsive ride, use more preload to optimize your bike’s geometry while riding.
Finally, remember that a suspension bike’s geometry is closely related to its spring rate and available travel.
Therefore, if you use less preload for one ride, your bike’s handling may feel less stable or predictable because you have less suspension travel than usual.
Similarly, if you use more preload for one ride, your bike may handle poorly at low speeds because it will have more initial spring rates than usual.
Does Preload Affect Ride Quality?
No, it doesn’t. That said, preload does affect shock and fork performance in other ways that can change your ride quality.
For example, the preload on your bike influences how much air pressure is in your fork or shock.
There’s a straightforward relationship between the volume of air (or fluid) and pressure—more volume leads to more pressure—but a good suspension setup doesn’t rely on adjusting preload to achieve its tuning.
However, it can be used as a starting point to find your ideal air pressure for riding.
Conclusion
Preload sets the shock or spring to the appropriate range of operation within the suspension’s travel.
The amount of preload used on your mountain bike suspension is essential as it affects traction, speed, and comfort. This article helps you understand that, so you get it right!
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